The present invention relates to sealing for use with a thrust reverser for turbo-fan engines.
Thrust reversers are provided, on modern aircraft turbo-fan engines, to reduce the stopping distance of the aircraft and to increase safety when landing on a wet or icy runway.
The thrust reversers are each comprised of two or more pivoting doors that are mounted in openings provided in a shroud or nacelle which surrounds the engine and defines an annular passage for the jet flow from the engine, said doors being adapted to pivot about axes, from a stowed position to a deployed position.
In the stowed position, the doors form a portion of said shroud and do not interfere with said flow, so that the forward thrust of the engine is allowed to continue directly rearwards along said annular passage.
In the deployed position, the doors are pivoted about the pivot axis to block the flow and redirect it in a forward direction, thereby producing a breaking force to stop the aircraft.
The primary objective of the present invention is to provide complete sealing in the stowed position. More precisely, a seal is required between the pivoting doors and the fixed structure in order to prevent pressure leakage of the jet flow, thereby insuring high forward thrust performance.
The sealing design is particularly important to attain the optimum forward thrust performance.
A prior art thrust reverser system incorporating pivoting doors is shown in U.S. Pat. No. 4 485,970 Fournier. In this prior art system, the seal is installed on the periphery of the pivoting doors.
French patent No. 2 601 077 and U.S. Pat. No. 4,410,152, both in the name of Kennedy, show a seal installed on the fixed structure within which the doors are pivoted. More precisely, in French patent No. 2 601 077, a seal 20 is installed on an extension 18 of the inner skin of the shroud, at the forward end of the opening in which the door is mounted. Seal 20 is linked by seals 20a, provided on longitudinal beams, to a seal 17a installed on a ring which projects from the deflection well at the rearward end of the opening. In U.S. Pat. No. 4,410,152, sealing at the front of the door, in the stowed position, is provided by a seal 28 fixed to the front of an internal wall PI integral with the fixed structure. The position and size of seal 28 are such that said seal prevents leak of flow towards the front of the doors only.
The present invention is comprised of a main seal that is installed on the fixed structure with a separate annular seal that is installed around the actuator body. A housing around the actuator body provides a guide or track for the annular seal.
The forward part of the main seal is located considerably aft to reduce the load on the doors, by reducing the surface exposed to the static pressure of the jet flow. This is further explained in the detailed description of the invention.